The present invention relates, generally, to an apparatus for concurrently applying to a substrate a plurality of substantially parallel strips of an adhesive discharged from a plurality of discharging units transported over the substrate by the apparatus. In particular, the adhesive applicator of the invention can be employed with an adhesive that is the reaction product of two adhesive reactants that are mixed and reacted as the adhesive is applied to the substrate.
There are a number of circumstances where an apparatus for concurrently applying a plurality of strips of an adhesive can be advantageously employed. For example, the construction of roofs for commercial and industrial buildings, typically, involves, as a first step, installing a corrugated steel decking having alternating peaks, or ribs, and valleys, or flutes. Thereafter, one or more layers of an insulating material are placed over the decking. Finally, one or more layers of a waterproof covering are placed over the insulating material. Conventionally, adhesives are used to secure the steel decking and the various layers of roofing materials together to form a, more-or-less, unitary covering for the roof. Such roofs, usually, are quite large, encompassing many square feet and, in some instances, the roofs cover several acres. Taking into account the sizes of the roofs that can be involved and the fact that several layers of roofing materials, typically, are applied, it is highly desirable that an apparatus be available that can rapidly apply large volumes of the adhesive to a relatively wide section of a roof in a single pass of the apparatus over the roofing materials.
It is important, of course that the adhesive used establish a sound bond between the layers of roofing materials to which it is applied. In this regard, it has been found that two-part, or two-component, adhesives are effective in establishing a good bond between layers of the roofing materials. These types of adhesives are the reaction products of two adhesive reactants that are mixed and react to form the two-part adhesives. In most cases, the two adhesive reactants cannot be mixed and reacted until the adhesives are applied to the roofing materials because the adhesives cure and set-up quite rapidly after the adhesive reactants are mixed. Consequently, any apparatus used to apply a two-part adhesive, preferably, has the ability to mix the two adhesive reactants forming the adhesive as the adhesive is applied to the roofing materials.